Proration calculator
Work out what to charge, or credit, when a customer changes subscription plan part-way through a billing period. Free, no sign-up, nothing leaves your browser.
Prices are per billing period. This splits the period by days; some billing systems work by the second or round differently.
How proration works
Proration means charging only for the part of a billing period a customer actually used. When someone upgrades part-way through, the old plan's unused value is set against the new plan's cost for the days left, and the customer pays the difference now, then the full new price from the next billing date.
When to prorate
Proration feels fair to customers who upgrade and makes it easier to say yes to a bigger plan. For downgrades, many businesses keep it simple: the lower price starts at the next billing date, with no refund for the current period. Whatever you choose, say so clearly before the customer changes plan.
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